Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 274,806	$ 286,042	$ 783,019	$ 690,608
Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	197,785	204,090	584,764	482,270
Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	74,258	63,524	175,264	155,773
Others
Disaggregation of Revenue [Line Items]
Revenue	2,763	18,428	22,991	52,565
Solar power systems sales and EPC services
Disaggregation of Revenue [Line Items]
Revenue	267,544	262,547	741,853	628,335
Solar power systems sales and EPC services | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	191,016	195,686	568,303	458,141
Solar power systems sales and EPC services | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	73,840	58,507	170,403	147,221
Solar power systems sales and EPC services | Others
Disaggregation of Revenue [Line Items]
Revenue	2,688	8,354	3,147	22,973
Operations and maintenance
Disaggregation of Revenue [Line Items]
Revenue	75	14,733	23,463	37,288
Operations and maintenance | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Operations and maintenance | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	4,659	3,619	7,696
Operations and maintenance | Others
Disaggregation of Revenue [Line Items]
Revenue	75	10,074	19,844	29,592
Residential leasing
Disaggregation of Revenue [Line Items]
Revenue	1,284	3,523	3,937	9,083
Residential leasing | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	1,284	3,523	3,937	9,083
Residential leasing | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Residential leasing | Others
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Solar services
Disaggregation of Revenue [Line Items]
Revenue	5,903	5,239	13,766	15,902
Solar services | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	5,485	4,881	12,524	15,046
Solar services | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	418	358	1,242	856
Solar services | Others
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0	$ 0	$ 0